1. Field of the Invention
The present invention relates to a testing system module for printed circuit board. More particularly, the present invention relates to a testing system module for testing short circuit, open circuit and extreme low leakage current of printed circuit board.
2. Prior Art
In the manufacturing process of printed circuit board, some electrical defects such as short circuit, open circuit, and leakage current would be caused by outside factors. Moreover, evolutions of printed circuit board are high-density, fine pitch, and multi-layer. Therefore, it would cause more cost wasting if the bad board could not be found in time. Besides the improvement of the control of manufacturing process of printed circuit board, improvement of testing technology of printed circuit board is also a good way for manufacturer to reduce scraped rate and raise quality of produce.
In tradition, the way of testing electricity of printed circuit board comprises that using three equipments to perform, which are dedicated test equipment, universal grid test equipment, and flying probe test equipment.
Regarding to dedicated test equipment, which comprises a fixture, such as a dial of testing electricity of printed circuit board. The fixture is only matched one type of printed circuit board. The other types of printed circuit board aren't tested by this dedicated test equipment. Moreover, the fixture would not be reused. Therefore, it wastes cost very much. Otherwise, leakage current of printed circuit board tested by dedicated test equipment lacks stability. The testing data lacks stability that the testing data are not accuracy and the extreme low leakage current, such as nano-ampere level or lower leakage current, could not be tested by the dedicated test equipment.
Universal grid test equipment has a big-size dial being fixture, and the big-size dial has many grids which has testing point. Thus, varied kinds of printed circuit board could be tested by the universal grid test equipment, and the universal grid test equipment does not need to change the fixture. However, as well as dedicated test equipment, leakage current of printed circuit board tested by dedicated test equipment also lacks stability. Moreover, the testing density of printed circuit board tested by universal grid test equipment has limitation. When the printed circuit board is a high-density board, the high-density board isn't tested by the universal grid test equipment.
Flying probe test equipment which merely has two probes to move on x, y, and z axes and to test any testing point of printed circuit board, therefore, it doesn't need more expensive fixture for testing. However, using flying probe test equipment to test printed circuit board still couldn't test the current range of IC testing level. Therefore, it would affect the efficiency and quality of further testing fabrication when the printed circuit board that current range of IC testing level of printed circuit board aren't tested is used to test IC. In order to solve the problem that extreme low leakage current of printed circuit board aren't tested by flying probe test equipment, in general, the testing process of this portion would be performed by extra-manpower. However, it not only wastes manpower but also adds cost of product.
Moreover, when the testing system module tests the printed circuit boards, the X, Y and Z coordinates are inputted in the controller to make the probe contacts on the printed circuit boards. However, the surface of the printed circuit boards is not so flat, and the rough surface of the printed circuit boards makes the probe not to contact the printed circuit boards precisely. Measurement inaccuracy or leakage current therefore happens.
Therefore, it's needed to find a testing system module which could combine the function of auto-continuingly testing and the function of accurately testing leakage current of printed circuit board, and keep the probe contacting the printed circuit boards precisely. Moreover, extreme low leakage current could be tested automatically, the cost of manpower and time could be saved, and the stability of testing data could be promoted.